A method for controlling a coordinate measuring apparatus of the above kind is, for example, disclosed in U.S. Pat. No. 5,491,638. For scanning the workpiece including a plurality of geometric elements, there are a plurality of different probe pins available which can be attached so as to be exchangeable on the probe head of the coordinate measuring apparatus with the probe head being moveable in the coordinate directions. For this purpose, the probe pins are stored at the edge of the measuring region in a corresponding magazine. The probe pins have shafts of different orientations and contact bodies in the form of probe balls are attached to the ends of the probe shafts. Different probe shafts with their contact bodies attached thereto are used for measuring the different geometric elements of the workpiece.
The measuring sequence for measuring a geometric element can basically be generated in two different ways. The first possibility is the automatic generation of CAD data of the workpiece. For a geometric element to be contacted, the measuring points on the geometric element to be contacted are generated automatically from the CAD data of the workpiece. For example, to measure a planar surface of the workpiece, which is defined by the geometric element “plane”, a two-dimensional measuring point raster could automatically be developed which defines the points on the plane to be contacted. Alternatively, the measuring points to be contacted can also be recorded by the operator of the coordinate measuring apparatus for the geometric element in a so-called teach-in method. For this purpose, the operator of the coordinate measuring apparatus contacts the desired points to be contacted on the particular geometric element of a workpiece via the coordinate measuring apparatus. The coordinate measuring apparatus is, in this case, controlled manually by the operator of the apparatus.
Common to both methods is, however, that the person who develops the measurement sequence must determine one or several suitable probe shafts with which the measuring points of the geometric element are to scanned. This method is time intensive. Especially in measurement sequences wherein the operator of the coordinate measuring apparatus must record the measuring points to be scanned in a teach-in method, it occurs that, with the use of complex probe pins, the operator of the coordinate measuring apparatus inadvertently scans the measuring points to be contacted on the geometric element with another probe shaft than the one which is adjusted in the operating program of the coordinate measuring apparatus. This leads to the situation that completely incorrect measurement values are recorded. This has the consequence that all measuring points, which are measured up to now, must be recorded anew with the correct probe pin.